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Journal article
Persistent declines in sightings of manta and devil rays (mobulidae) at a global hotspot in southern mozambique
Environmental Biology of Fishes, Vol.108(4), pp.749-765
2025
Abstract
Mobulid rays are among the most vulnerable of chondrichthyans to overexploitation by fisheries due to their low population growth rates. In locations where catch data are lacking, long-term sightings data can provide valuable insight to infer population trends and status. We recorded underwater sighting data of reef manta rays (Mobula alfredi), oceanic manta rays (M. birostris), and shorthorned pygmy devil rays (M. kuhlii) between 2003 and 2023 in the waters off Praia do Tofo in the Inhambane Province, southern Mozambique, one of the major global hotspots for these rays. We modelled sightings data using a hierarchical generalised linear mixed model framework to account for a suite of environmental variables when examining temporal trends. Raw trend models including only ‘year’ as a predictor showed a 99% decline in sightings of reef manta rays, a 92.5% decline in oceanic manta ray sightings, and an 81.3% decline in devil ray sightings over the 20-year study period. The declining trends persisted for reef and oceanic manta rays once a suite of temporal and environmental variables were accounted for, indicating that the declines were driven by external factors not tested in the models. For shorthorned pygmy devil rays, models that incorporated environmental variables did not retain year as a significant predictor and showed a reduced overall decline in sightings of 36.5%. This indicates that the tested predictors were responsible for approximately half of the observed decline. Anthropogenic factors, particularly fisheries mortality, are likely to have played a significant role in the declining sightings of these three Threatened species. Improved conservation and management measures at a national and international level are critical to prevent further declines, which may otherwise lead to localised extinction.
Details
- Title
- Persistent declines in sightings of manta and devil rays (mobulidae) at a global hotspot in southern mozambique
- Authors
- Stephanie K. Venables (Corresponding Author) - Marine Megafauna FoundationChristoph A. Rohner - Marine Megafauna FoundationAnna L. Flam - Marine Megafauna FoundationSimon J. Pierce (Corresponding Author) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringAndrea D. Marshall - Marine Megafauna Foundation
- Publication details
- Environmental Biology of Fishes, Vol.108(4), pp.749-765
- Publisher
- Springer Dordrecht
- Date published
- 2025
- DOI
- 10.1007/s10641-024-01609-z
- ISSN
- 1573-5133; 0378-1909
- Copyright note
- © The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
- Data Availability
- Datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request.
- Grant note
- CAR and SJP were supported by Waterlust and Aqua-Firma. Field research between 2005 and 2012 was supported by grants from the Save Our Seas Foundation and funding from the University of Queensland. ADM was additionally supported with funding from National Geographic. General funding was provided by MMF Canada and MMF private donors. Manuscript write-up funding was supported by the Wildlife Conservation Society and the Manta Trust.
- Organisation Unit
- School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 991127096102621
- Output Type
- Journal article
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